| BMWG | R. Rosa, Ed. |
| Internet-Draft | C. Rothenberg |
| Intended status: Informational | UNICAMP |
| Expires: July 2, 2019 | M. Peuster |
| H. Karl | |
| UPB | |
| December 29, 2018 |
Methodology for VNF Benchmarking Automation
draft-rosa-bmwg-vnfbench-03
This document describes a common methodology for the automated benchmarking of Virtualized Network Functions (VNFs) executed on general-purpose hardware. Specific cases of benchmarking methodologies for particular VNFs can be derived from this document. Two open source reference implementations are reported as running code embodiments of the proposed, automated benchmarking methodology.
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The Benchmarking Methodology Working Group (BMWG) already presented considerations for benchmarking of VNFs and their infrastructure in [RFC8172]. Similar to the motivation given in [RFC8172], the following aspects motivate the need for VNF benchmarking: (i) pre-deployment infrastructure dimensioning to realize associated VNF performance profiles; (ii) comparison factor with physical network functions; (iii) and output results for analytical VNF development.
Even if many methodologies already described by the BMWG, e.g., self- contained black-box benchmarking, can be applied to VNF benchmarking scenarios, further considerations have to be made. This is, on the one hand, because VNFs, which are software components, do not have strict and clear execution boundaries and depend on underlying virtualization environment parameters as well as management and orchestration decisions [ETS14a]. On the other hand, can and should the flexible, software-based nature of VNFs be exploited to fully automate the entire benchmarking procedure end-to-end. This is an inherent need to align VNF benchmarking with the agile methods enabled by the concept of network function virtualization (NFV) [ETS14e] More specifically it allows: (i) the development of agile performance-focused DevOps methodologies for Continuous Integration and Delivery (CI/CD) of VNFs; (ii) the creation of on-demand VNF test descriptors for upcoming execution environments; (iii) the path for precise-analytics of extensively automated catalogues of VNF performance profiles; (iv) and run-time mechanisms to assist VNF lifecycle orchestration/management workflows, e.g., automated resource dimensioning based on benchmarking insights.
This document describes basic methodologies and guidelines to fully automate VNF benchmarking procedures, without limiting the automated process to a specific benchmark or infrastructure. After presenting initial considerations, the document first describes a generic architectural framework to setup automated benchmarking experiments. Second, the automation methodology is discussed, with a particular focus on experiment and procedure description approaches to support reproducibility of the automated benchmarks, a key challenge in VNF benchmarking. Finally, two independent, open-source reference implementations are presented. The document addresses state-of-the-art work on VNF benchmarking from scientific publications and current developments in other standardization bodies (e.g., [ETS14c] and [RFC8204]) wherever possible.
Common benchmarking terminology contained in this document is derived from [RFC1242]. Also, the reader is assumed to be familiar with the terminology as defined in the European Telecommunications Standards Institute (ETSI) NFV document [ETS14b]. Some of these terms, and others commonly used in this document, are defined below.
This document assumes VNFs as black boxes when defining their benchmarking methodologies. White box approaches are assumed and analysed as a particular case under the proper considerations of internal VNF instrumentation, later discussed in this document.
This document outlines a methodology for VNF benchmarking, specifically addressing its automation.
VNF benchmarking considerations are defined in [RFC8172]. Additionally, VNF pre-deployment testing considerations are well explored in [ETS14c].
Following ETSI's model in [ETS14c], we distinguish three methods for VNF evaluation:
Note: Verification and Dimensioning can be reduced to Benchmarking. Therefore, we focus on Benchmarking in the rest of the document.
VNF benchmarking procedures contain multiple aspects that may or may not be automated:
For the purposes of dissecting the automated execution procedures, consider the following definitions:
A generic VNF benchmarking architectural framework, shown in Figure 1, establishes the disposal of essential components and control interfaces, explained below, that enable the automation of VNF benchmarking methodologies.
+---------------+
| Manager |
Control | (Coordinator) |
Interface +---+-------+---+
+--------+-----------+ +-------------------+
| | |
| | +-------------------------+ |
| | | System Under Test | |
| | | | |
| | | +-----------------+ | |
| +--+------- + VNF | | |
| | | | | |
| | | +----+ +----+ | | |
| | | |VNFC|...|VNFC| | | |
| | | +----+ +----+ | | |
| | +----.---------.--+ | |
+-----+---+ | Monitor | : : | +-----+----+
| Agent | |{listeners}|----^---------V--+ | | Agent |
|(Sender) | | | Execution | | |(Receiver)|
| | | | Environment | | | |
|{Probers}| +-----------| | | |{Probers} |
+-----.---+ | +----.---------.--+ | +-----.----+
: +---------^---------V-----+ :
V : : :
:................>.....: :............>..:
Stimulus Traffic Flow
Figure 1: Generic VNF Benchmarking Setup
A deployment scenario realizes the instantiation of physical and/or virtual of components of a Generic VNF Benchmarking Architectural Framework needed to habilitate the execution of an automated VNF benchmarking methodology.
The following considerations hold for deployment scenarios:
Portability is an intrinsic characteristic of VNFs and allows them to be deployed in multiple environments. This enables various benchmarking setups in varied deployment scenarios. A VNF benchmarking methodology must be described in a clear and objective manner in order to allow effective repeatability and comparability of the test results. Those results, the outcome of a VNF benchmarking process, must be captured in a VNF Benchmarking Report (VNF-BR), as shown in Figure 2.
______________
+--------+ | |
| | | Automated |
| VNF-BD |--(defines)-->| Benchmarking |
| | | Process |
+--------+ |______________|
V
|
(generates)
|
v
+-------------------------+
| VNF-BR |
| +--------+ +--------+ |
| | | | | |
| | VNF-BD | | VNF-PP | |
| | {copy} | | | |
| +--------+ +--------+ |
+-------------------------+
Figure 2: VNF benchmarking process inputs and outputs
A VNF Benchmarking Report consist of two parts:
A VNF-BR correlates structural and functional parameters of VNF-BD with extracted VNF benchmarking metrics of the obtained VNF-PP. The content of each part of a VNF-BR is described in the following sections.
VNF Benchmarking Descriptor (VNF-BD) -- an artifact that specifies a method of how to measure a VNF Performance Profile. The specification includes structural and functional instructions and variable parameters at different abstraction levels (e.g., topology of the deployment scenario, benchmarking target metrics, parameters of benchmarking components). VNF-BD may be specific to a VNF or applicable to several VNF types. A VNF-BD can be used to elaborate a VNF benchmark deployment scenario aiming at the extraction of particular VNF performance metrics.
The following items define the VNF-BD contents.
The definition of parameters concerning the descriptor file, e.g., its version, identidier, name, author and description.
General information addressing the target VNF(s) the VNF-BD is applicable, with references to any specific characteristics, i.e., the VNF type, model, version/release, author, vendor, architectural components, among any other particular features.
This section contains all information needed to describe the deployment of all involved functional components mandatory for the execution of the benchmarking tests addressed by the VNF-BD.
Information about the experiment topology, concerning the disposition of the components in a benchmarking setup (see Section 5). It must define the type of each component and how they are interconnected (i.e., interface, link and network characteristics). Acceptable topology descriptors might include references to external configuration files particular of orchestration technologies (e.g., TOSCA, YANG).
Involves the definition of execution environment requirements for the tests. Therefore, they concern all required capabilities needed for the execution of the target VNF and the other components composing the benchmarking setup. Examples of requirements include the allocation of CPUs, memory and disk for each component in the deployment scenario.
Involves the definition of execution environment policies to run the tests. Policies might specify the (anti)-affinity placement rules for each component in the topology, min/max allocation of resources, specific enabling technologies (e.g., DPDK, SR-IOV, PCIE) needed for each component.
Involves any specific configuration of benchmarking components in a setup described the the deployment scenario topology.
Specifies the details of each component in the described topology in the deployment scenario. For instante, it contains the role of each component and its particular parameters, as the cases detailed below:
The definition of parameters concerning the execution environment of the VNF-BD, for instance, containing name, description, plugin/driver, and parameters to realize the interface with an orchestration component responsible to instantiate each VNF-BD deployment scenario.
The definition of parameters concerning the execution of the benchmarking procedures, for instance, containing the number of repetitions for each trial, test, and the whole VNF-BD (method).
VNF Performance Profile (VNF-PP) -- defines a mapping between resources allocated to a VNF (e.g., CPU, memory) as well as assigned configurations (e.g., routing table used by the VNF) and the VNF performance metrics (e.g., throughput, latency, CPU, memory) obtained in a benchmarking test conducted using a VNF-BD. Logically, packet processing metrics are presented in a specific format addressing statistical significance (e.g., median, standard deviation, percentiles) where a correspondence among VNF parameters and the delivery of a measured VNF performance exists.
The following items define the VNF-PP contents.
Execution environment information is has to be included in every VNF-PP and is required to describe the environment on which a benchmark test was actually executed.
Ideally, any person who has a VNF-BD and its complementing VNF-PP with its execution environment information available, must be able to reproduce the same deployment scenario and VNF benchmarking tests to obtain identical VNF-PP measurement results.
If not already defined by the VNF-BD deployment scenario requirements (Section 6.1.3), for each component in the deployment scenario of the VNF benchmarking setup, the following topics must be detailed:
Optionally, a VNF-PP execution environment might contain references to an orchestration description document (e.g., HEAT template) to clarify technological aspects of the execution environment and any specific parameters that it might contain for the VNF-PP.
Measurement results concern the extracted metrics, output of benchmarking procedures, classified into:
Depending on the configuration of the benchmarking setup and the planned use cases for the resulting VNF-PPs, measurement results can be stored as raw data, e.g., time series data about CPU utilization of the VNF during a throughput benchmark. In the case of VNFs composed of multiple VNFCs, those resulting data should be represented as vectors, capturing the behavior of each VNFC, if available from the used monitoring systems. Alternatively, more compact representation formats can be used, e.g., statistical information about a series of latency measurements, including averages and standard deviations. The exact output format to be used is defined in the complementing VNF-BD (Section 6.1).
The representation format of a VNF-PP must be easily translated to address the combined set of classified items in the 3x3 Matrix Coverage defined in [RFC8172].
The methodology for VNF Benchmarking Automation encompasses the process defined in Figure 2, i.e., the procedures that translate a VNF-BD into a VNF-PP composing a VNF-BR by the means of the components specified in Figure 1. This section details the sequence of events that realize such process.
Before the execution of benchmark tests, some procedures must be performed:
Satisfied all the pre-execution procedures, the automated execution of the tests specified by the VNF-BD follow:
After the process of a VNF-BD, generated the associated VNF-BR, some procedures must be guaranteed:
As described in [RFC8172], VNF benchmarking might require to change and adapt existing benchmarking methodologies. More specifically, the following cases need to be considered.
VNFs are usually deployed inside containers or VMs to build an abstraction layer between physical resources and the resources available to the VNF. According to [RFC8172], it may be more representative to design experiments in a way that the VMs hosting the VNFs are operating at maximum of 50% utilization and split the workload among several VMs, to mitigateside effects of overloaded VMs. Those cases are supported by the presented automation methodologies through VNF-BDs that enable direct control over the resource assignments and topology layouts used for a benchmarking experiment.
One of the main challenges of NFV is to create isolation between VNFs. Benchmarking the quality of this isolation behavior can be achieved by Agents that take the role of a noisy neighbor, generating a particular workload in synchrony with a benchmarking procedure over a VNF. Adjustments of the Agent's noisy workload, frequency, virtualization level, among others, must be detailed in the VNF- BD.
Hardware and software components will fail or have errors and thus trigger healing actions of the benchmarked VNFs (self-healing). Benchmarking procedures must also capture the dynamics of this VNF behavior, e.g., if a container or VM restarts because the VNF software crashed. This results in offline periods that must be captured in the benchmarking reports, introducing additional metrics, e.g., max. time-to-heal. The presented concept, with a flexible VNF-PP structure to record arbitrary metrics, enables automation of this case.
Having software based network functions and the possibility of a VNF to be composed by multiple components (VNFCs), internal events of the VNF might trigger changes in VNF behavior, e.g.,activating functionalities associated with elasticity such as automated scaling. These state changes and triggers (e.g. the VNF's scaling state) must be captured in the benchmarking results (VNF-PP) to provide a detailed characterization of the VNF's performance behavior in different states.
As described in [RFC8172], does the sheer number of test conditions and configuration combinations create a challenge for VNF benchmarking. As suggested, machine readable output formats, as they are presented in this document, will allow automated benchmarking procedures to optimize the tested configurations. Approaches for this are, e.g., machine learning-based configuration space sub-sampling methods, such as [Peu-c].
A benchmarking setup must be able to define scenarios with and without monitoring components inside the VNFs and/or the hosting container or VM. If no monitoring solution is available from within the VNFs, the benchmark is following the black-box concept. If, in contrast, those additional sources of information from within the VNF are available, VNF-PPs must be able to handle these additional VNF performance metrics.
In general, automated VNF benchmarking tests as herein described must capture relevant causes of performance variability. Concerning a deployment scenario, influencing aspects on the performance of a VNF can be observed in:
The listed influencing aspects must be carefully analyzed while automating a VNF benchmarking methodology.
There are two open source reference implementations that are build to automate benchmarking of Virtualized Network Functions (VNFs).
The software, named Gym, is a framework for automated benchmarking of Virtualized Network Functions (VNFs). It was coded following the initial ideas presented in a 2015 scientific paper entitled “VBaaS: VNF Benchmark-as-a-Service” [Rosa-a]. Later, the evolved design and prototyping ideas were presented at IETF/IRTF meetings seeking impact into NFVRG and BMWG.
Gym was built to receive high-level test descriptors and execute them to extract VNFs profiles, containing measurements of performance metrics – especially to associate resources allocation (e.g., vCPU) with packet processing metrics (e.g., throughput) of VNFs. From the original research ideas [Rosa-a], such output profiles might be used by orchestrator functions to perform VNF lifecycle tasks (e.g., deployment, maintenance, tear-down).
The proposed guiding principles, elaborated in [Rosa-b], to design and build Gym can be composed in multiple practical ways for different VNF testing purposes:
In [Rosa-b] Gym was utilized to benchmark a decomposed IP Multimedia Subsystem VNF. And in [Rosa-c], a virtual switch (Open vSwitch - OVS) was the target VNF of Gym for the analysis of VNF benchmarking automation. Such articles validated Gym as a prominent open source reference implementation for VNF benchmarking tests. Such articles set important contributions as discussion of the lessons learned and the overall NFV performance testing landscape, included automation.
Gym stands as one open source reference implementation that realizes the VNF benchmarking methodologies presented in this document. Gym is being released open source at [Gym]. The code repository includes also VNF Benchmarking Descriptor (VNF-BD) examples on the vIMS and OVS targets as described in [Rosa-b] and [Rosa-c].
Another software that focuses on implementing a framework to benchmark VNFs is the "5GTANGO VNF/NS Benchmarking Framework" also called "tng-bench" (previously "son-profile") and was developed as part of the two European Union H2020 projects SONATA NFV and 5GTANGO [tango]. Its initial ideas were presented in [Peu-a] and the system design of the end-to-end prototype was presented in [Peu-b].
Tng-bench aims to be a framework for the end-to-end automation of VNF benchmarking processes. Its goal is to automate the benchmarking process in such a way that VNF-PPs can be generated without further human interaction. This enables the integration of VNF benchmarking into continuous integration and continuous delivery (CI/CD) pipelines so that new VNF-PPs are generated on-the-fly for every new software version of a VNF. Those automatically generated VNF-PPs can then be bundled with the VNFs and serve as inputs for orchestration systems, fitting to the original research ideas presented in [Rosa-a] and [Peu-a].
Following the same high-level VNF testing purposes as Gym, namely: Comparability, repeatability, configurability, and interoperability, tng- bench specifically aims to explore description approaches for VNF benchmarking experiments. In [Peu-b] a prototype specification for VNF-BDs is presented which not only allows to specify generic, abstract VNF benchmarking experiments, it also allows to describe sets of parameter configurations to be tested during the benchmarking process, allowing the system to automatically execute complex parameter studies on the SUT, e.g., testing a VNF's performance under different CPU, memory, or software configurations.
Tng-bench was used to perform a set of initial benchmarking experiments using different VNFs, like a Squid proxy, an Nginx load balancer, and a Socat TCP relay in [Peu-b]. Those VNFs have not only been benchmarked in isolation, but also in combined setups in which up to three VNFs were chained one after each other. These experiments were used to test tng-bench for scenarios in which composed VNFs, consisting of multiple VNF components (VNFCs), have to be benchmarked. The presented results highlight the need to benchmark composed VNFs in end-to-end scenarios rather than only benchmark each individual component in isolation, to produce meaningful VNF- PPs for the complete VNF.
Tng-bench is actively developed and released as open source tool under Apache 2.0 license [tng-bench].
Benchmarking tests described in this document are limited to the performance characterization of VNFs in a lab environment with isolated network.
The benchmarking network topology will be an independent test setup and MUST NOT be connected to devices that may forward the test traffic into a production network, or misroute traffic to the test management network.
Special capabilities SHOULD NOT exist in the VNF benchmarking deployment scenario specifically for benchmarking purposes. Any implications for network security arising from the VNF benchmarking deployment scenario SHOULD be identical in the lab and in production networks.
This document does not require any IANA actions.
The authors would like to thank the support of Ericsson Research, Brazil. Parts of this work have received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. H2020-ICT-2016-2 761493 (5GTANGO: https://5gtango.eu).
| [ETS14a] | ETSI, "Architectural Framework - ETSI GS NFV 002 V1.2.1", Dec 2014. |
| [ETS14b] | ETSI, "Terminology for Main Concepts in NFV - ETSI GS NFV 003 V1.2.1", Dec 2014. |
| [ETS14c] | ETSI, "NFV Pre-deployment Testing - ETSI GS NFV TST001 V1.1.1", April 2016. |
| [ETS14d] | ETSI, "Network Functions Virtualisation (NFV); Virtual Network Functions Architecture - ETSI GS NFV SWA001 V1.1.1", December 2014. |
| [ETS14e] | ETSI, "Report on CI/CD and Devops - ETSI GS NFV TST006 V0.0.9", April 2018. |
| [RFC1242] | S. Bradner, "Benchmarking Terminology for Network Interconnection Devices", July 1991. |
| [RFC8172] | A. Morton, "Considerations for Benchmarking Virtual Network Functions and Their Infrastructure", July 2017. |
| [RFC8204] | M. Tahhan, B. O'Mahony, A. Morton, "Benchmarking Virtual Switches in the Open Platform for NFV (OPNFV)", September 2017. |